The present invention relates to an electric motor that has a retainer disc mounted on a bearing plate for holding contacts. The electric motor is provided, in particular, for applications in motor vehicles, for example, for driving an electromechanical roll stabilizer, for driving a steering system, or for driving a ride-height control system. In addition, the invention relates to a method for assembling the motor according to the invention.
DE 10 2012 205 754 A1 shows a housing for a rotating electrical machine with a bearing plate between a housing outer part and a housing inner part. A rotor position sensor is mounted on a sensor holder.
DE 10 2010 000 710 A1 shows a bearing plate for an electric motor that has a current guide that is designed to connect at least one winding of the stator to a current connection.
From DE 299 01 976 U1, an electric motor is known with an arrangement for monitoring the rotational speed in which a sensor element is arranged so that it can be connected to an inner wall of a bearing plate.
FIG. 3 shows a cross section of a detail of an electric motor according to the prior art. The electric motor comprises a stator 01 and a rotor 02. The rotor 02 can be rotated relative to the stator 01 about an axis 03. The rotor 02 comprises a rotor shaft 04 that is supported so that it can rotate in a bearing 06. The bearing 06 sits in a bearing plate 07 that is mounted on a motor housing 08. The motor housing 08 with the stator 01 located therein and bearing plate 07 are mounted within a system housing 09.
The stator 01 comprises an electromagnet (hidden in the illustration) out of which multiple conductors 11 project for the electrical connection of the electromagnet. The electromagnet of the stator 01 comprises a laminated core with windings (not shown) located on this core. The conductors 11 are guided through the bearing plate 07. On the bearing plate 07 there is a retainer disc 12 made from a plastic for holding contacts 13. The retainer disc 12 is arranged coaxial to the axis 03 and axially next to the bearing plate 07. The retainer disc 12 is mounted on one side with screws 14 on the bearing plate 07. On the other side, the retainer disc 12 has guide pins 16 that determine the radial position of the retainer disc 12. In addition, the contacts 13 are mounted on the conductors 11 of the electromagnet of the stator 01 so that the position of the retainer disc 12 is overdetermined relative to the bearing plate 07. This can lead to mechanical voltages on the contacts 13 that can have effects on a power electronics module 17 that is connected rigidly to the contacts 13 with the help of contact screws 18. In particular, this can lead to deformation of a printed circuit board 19 of the power electronics module 17. The deformation is shown by a dimension s.
The retainer disc 12 further has sensor guide pins 21 for determining the radial position of a sensor electronics module 22. The sensor electronics module 22 is opposite an angular position and rotational speed encoder 23 that is made from a permanently magnetic material and is mounted on the rotor shaft 04. The sensor electronics module 22 and the angular position and rotational speed encoder 23 form a rotational speed sensor for measuring the rotational speed of the electric motor. The over-fixing of the position of the retainer disc 12 described above can lead to displacements of the retainer disc 12 which lead, in turn, to displacements of the sensor electronics module 22 in the form of an eccentricity e and therefore can negatively affect the accuracy of the rotational speed sensor.
FIG. 4 shows the retainer disc 12 shown in FIG. 3 in a plan view. The screws 14 (shown in FIG. 1) are guided by circular round fastener openings 24 in the retainer disc 12. The fastener openings 24 are each formed within a metallic insert bushing that is inserted into the retainer disc 12.